Cover lift pin



A. BODENSCHATZ 3,015,709

COVER LIFT PIN Jan. 2, 1962 Filed April 9, 1959 2 Sheets-Sheet 1INVENTOR. flz/awr 600.5306472 Jan. 2, 1962 A. BODENSCHATZ 3,015,709

COVER LIFT PIN Filed April 9, 1959 2 Sheets-Sheet 2 United states PatentQhdce EfllSJW Patented Jan. 2, 19%.?!

3,015,709 COVER LIFT PIN August Bodenschatz, Philadelphia, Pa., assrgnorto I-T-E Circuit Breaker Company, Philadelphia, Pa, a corporation ofPerms lvania Filed Air. 9, 1959, Ser. No. 805,183 9 Claims. (Cl.200-114) The instant invention generally relates to coordinated circuitbreaker and fuse means which are mountedto a common base and moreparticularly to means for assisting in the removal of the fuse meansfrom the base.

A molded case circuit interrupter unit wherein a c1rcuit breaker andfuse means are mounted to a common base is described in detail incopending application Serial No. 622,042 filed November 14, 1956, nowPatent l lo. 2,924,688 entitled End Mounting of a Current Limit-mgDevice Associated with a Circuit Breaker with William Harold Edmunds asinventor, and assigned to the assignee of the instant invention.

The fuses of this type circuit interrupter are mounted to a cover whichi removable from the base. The circuit breaker is usually a three-phaseunit so that removal of the cover to which the fuses are secured resultsin the severing of six electrical connections.

Each of these electrical connections is made by a stud, projecting fromthe fuse, which is entered into a tulip type terminal connector mountedto the base. The tulip connector includes a biasing means which forces aplurality of fingers snugly against the fuse stud. This creates a goodelectrical connection and at the same time a mechanical force ofconsiderable magnitude which holds the stud and tulip connectedtogether. Thi mechanical force, when multiplied six times, makes itextremely difficult to separate the cover holding the fuses from thebase.

In prior art circuit breakers of this type, it was necessary to rock thecover back and forth or to work a screw-driver between the cover andbase on both sides of the circuit breaker in order to remove the fusemeans from the base. In many installations, because of a front sheet inthe panelboard to which the circuit breaker is mounted, the juncturebetween the base and cover was not accessible so that a screw-drivercould not be conveniently entered at this juncture.

The instant invention provides means which assist in the separation ofthe cover fro-m the base. This assist means comprises a lift pin whichis mounted to the-cover and is operatively positioned in close proximityto one of the screws which fastens the cover to the base. When it isdesired to remove the cover from the base, the fastening screws areturned out of the base so that the ends thereof opposite the screw headsrest at the tops of the threaded base apertures which receive thesecuring screw. Now the screw heads are raised above the outer surfaceof the cover.

The tip of a screw driver is then placed under the head of the lift pinand the blade of the screw-driver is made to bear against one of thescrew heads. By bearing on the handle of the screw-driver so as to applya force acting toward the cover, the head of the securing screw acts asa fulcrum with the tip of the screw-driver raising the lift pin and inso doing lifting the cover which is free to move with respect to thesecuring screw.

The movement of the cover is sufiicient to move the fuse studs withrespect to the tulip connectors to a position wherein the mechanicalforce exerted by the tulip connectors against the fuse studs ismaterially decreased or completely eliminated. Thereafter the fuse coverand fuses may readily be removed from the base by hand.

The lift pin is normally disposed with the head thereof in a recess atthe outer surface of the fuse cover with a spring means biasing the liftpin to this position. In this position, the head of the lift pin isflush with the outer surface of the cover. The recess for the lift pinhead is provided with extension notches into which the screw-driver tipmay be entered so that the tip may conveniently be placed below the liftpin head when it is desired to remove the fuses from the base at allother times the spring means biases the lift pin to a position where thehead thereof is flush with the outer surface of the fuse cover.

Accordingly, a primary object of the instant invention is to providenovel means for assisting in the removal of a fuse mean of a circuitinterrupter from the base to which it is mounted.

Another object is to provide novel arrangement for prying a fuse coverand the fuses mounted thereto loose from the base to which it ismounted.

Still another object of my invention is to provide a retractable liftpin for a base cover which will assist in the removal of the cover fromthe base.

These as well as other objects of the instant invention shall becomereadily apparent after reading the following description of theaccompanying drawings in which;

FIGURE 1 is a partially exploded perspective of a molded case circuitinterrupter unit wherein a circuit breaker and coordinated fuse meansare mounted to a common base with the fuse means being removable fromthe base.

FIGURE 2 is a crosse-section of the removable fuse means taken throughline 22 of FIGURE 1 looking in the direction of arrows 22.

FIGURE 3 is a cross-section of the fuse means housing, with the fusesremoved, taken through line 3-3 of FIGURE 1 looking in the direction ofthe arrows 3-3.

FIGURE 4 is a fragmentary plan view of the fuse means cover looking inthe direction of arrows 4-4 of FIGURE 2.

Now referring to the figures, circuit interrupter unit It) is of thetype described in detail in the aforesaid copending application SerialNo. 622,042. Circuit interrupter unit 10 generally comprises a commonbase 1 1 having circuit breaker 12 and fuse means 13 mounted thereto.Circuit breaker 12 includes a molded cover 14 removably secured to base11 by fasteners 15. Operating handle 16 extends through cover opening 17and is operatively connected to the cooperating contacts (not shown) ofcircuit breaker 12 for manual operation thereof. Circuit breaker 12 is athree-phase unit having three load terminals 18 only two of which areshown. A slidable pin 20 extends through cover 14 and provides themechanical connection between the operating mechanism of circuit breaker12 and fuse means 13 as will be hereinafter described.

Fuse means 13 comprises a current limiting fuse 21 in series with eachof the three-phases of circuit breaker 12. The fusible element (notshown) of fuse 21 is housed in cylindrical casing 22. Studs 23, 24, ateach end of casing 22 form the terminals for fuse 21.

The three fuses 21 are secured to fuse housing 67 by insulating strip 25and suitable fastening means (not shown). Internal formations 26 ofhousing 67 provide electrical barriers between adjacent studs 24 andadjacent studs 23. Fuse terminals 23, 24 are positioned to be enteredinto tulip connectors 18, 19, respectively, which are mounted to base 11when fuse means 13 is mounted to base 11. Screws 27, 28 are enteredthrough clearance apertures 29, 30, respectively, of fuse cover 24 withthe threads of screws 27, 28 mating with the threads of apertures 31,32, respectively, in base 11.

Fuse means 13 also includes common tripper bar 33 pivotally mounted at34 and biased thereabout in a counterclockwise direction by compressionspring 35 which bears against fuse cover 67 and upper extension 36 ofcommon tripper bar 33. When fuse means 13 is mounted to base 11,extension 37 of common tripper bar 33 engages slide pin 2%) forcing itto the right with respect to FIGURE 1 thereby forming the mechanicalconnection between fuse means 13 and circuit breaker 12. The functionand operation of this mechanical connection forms no part of the instantinvention. A complete discussion of this subject is found in theaforesaid copending application Serial No. 622,042.

Secured to fuse cover 67 midway between apertures 29, 30 is lift pin 40.The head 41 of lift pin 40 is normally disposed within recess 42 formedin the outer surface 48 of fuse cover 67, being urged to this positionby compression spring 43. One end of compression spring 43 bears againstthe inside surface of cover 67 while the other end of spring 43 bearsagainst washer 44 which is mounted to the shank 45 of pin 40.Selflocking nut 46 threaded to pin 40 serves to retain pin 46 to cover67. The head 41 of lift pin 40 is provided with an overhanging section47, a surface of which lies flush with outside surface 43 of cover 67when head 41 is disposed within recess 42.

When fuse means 13 is mounted to base 11, the garter springs 50 of thetulip connectors 18, 19 urge the contact members 51 of tulip connectors18, 19 firmly against the outer surfaces of fuse terminals 23, 24. Thiscreates a strong mechanical force acting to retain the connectionbetween studs 23, 24 and terminals 18, 19 so that a considerable forceis required to separate fuse means 13 from base 11.

Dismounting of fuse means 13 from base 11 is accomplished by firstremoving fastening screws 27, 28 from their respective threadedapertures 31, 32 so that the screw heads 52 are raised above the outersurface 48 of fuse cover 67 and the ends 53 of screws 27, 28 oppositeheads 52 rest on the top threads of threaded apertures 31, 32. The tip61 of screw-driver blade 60 is then forced under the head 41 of lift pin40 and another portion 62 of screw-driver blade 60 is brought to bearagainst head 52 of screw 28.

By applying force upon the screw-driver handle (not shown) in adirection toward the outside surface 48 of cover 67, lift pin 40 isfirst raised out of recess 42. At the time when washer 44 is forcedagainst the inner surface 64 of housing 24 by nut 46, continued movementof lift pin 40 will cause cover 67 to rise. This will also cause fuseterminals 23, 24 to rise being moved relative to their respective tulipconnectors 18, 19 to a position wherein the force exerted by gartersprings 50 is materially reduced. Now, fuse means 13 may be grasped byhand and dismounted from base 11 In order to simplify the working ofscrew-driver tip 61 beneath lift pin head 41, recess 42 is provided withwing notches 65, 66 which extend beyond the portion of recess 42occupied by head 41. Thus, when head 52 of securing screw 28 is utilizedas a fulcrum screw-driver, tip 61 is entered into wing notch 66, workedunder head extension 47, and then under the main portion of head 41 toabut the shank 45 of lift pin 40. Upon the removal of the screw-drivertip 61, compression spring 43 will retract lift pin 40 to the positionwherein the top of head 41 is flush with the outside surface 48 of cover67.

Thus, I have provided a novel means for assisting the dismounting offuse means 13 from base 11. It is readily seen that the distance betweenscrew-driver blade portion 62 and the point on the screw-driver handlewhere force is applied is considerably longer than the distance betweenblade portion 62 and blade tip 61. The mechanical advantage therebyobtained readily enables a person to overcome the mechanical forcecreated by garter springs 50 of tulip connectors 16, 19 which tends toretain the connections between fuse stud terminals 23, 24 and theirrespective tulip connectors 18, 19.

In the foregoing, I have described my invention only in connection withpreferred embodiments thereof. Many variations and modifications of theprinciples of my invention within the scope of the description hereinare obvious. Accordingly, I prefer to be bound not by the specificdisclosure herein but only by the appending claims.

I claim:

1. A circuit interrupter comprising a base, a circuit breaker mounted tosaid base, a fuse means operatively connected to said circuit breaker,securing means removably mounting said fuse means to said base; saidfuse means being comprised of a cover and a fuse mounted to said cover;said fuse having a first and a second terminal; a third and a fourthterminal mounted to said base and removably engaged with said first andsaid second terminals, respectively; means carried by said cover andoperatively positioned with respect to said securing means so as to beengageable by and cooperable with a prying device which utilizes saidsecuring means as a fulcrum to thereby readily overcome the mechanicalforce which accompanies the engagement between said fuse terminals andsaid base mounted terminals when said fuse means is mounted to saidbase; said means comprising a lift pin having an enlarged head; saidsecuring means being comprised of a screw passing through a clearancehole of said cover; one end of said screw having an enlarged head andthe other end of said screw having threads mated with a threadedaperture in said base; said head being positioned beyond a first surfaceof said cover when said screw is at the entrance of said aperture; saidmeans carried by said cover extending above said cover first surfacewhen the prying device is manipulated to overcome the aforesaidmechanical force.

2. A circuit interrupter comprising a base, a circuit breaker mounted tosaid base, a fuse means operatively connected to said circuit breaker,securing means removably mounting said fuse means to said base; saidfuse means being comprised of a cover and a fuse mounted to said cover;said fuse having a first and a second terminal; a third and a fourthterminal mounted to said base and removably engaged with said first andsaid second terminasl, respectively; means carried by said cover andoperatively positioned with respect to said securing means so as to beengageable by and cooperable with a prying device which utilizes saidsecuring means as a fulcrum to thereby readily overcome the mechanicalforce which accompanies the engagement between said fuse terminals andsaid base mounted terminals when said fuse means is mounted to saidbase; said securing means being comprised of a screw passing through aclearance hole of said cover; one end of said screw having an enlargedhead and the other end of said screw having threads mated with athreaded aperture in said base; said head being positioned beyond afirst surface of said cover when said screw is at the entrance of saidaperture; said means carried by said cover extending above said coverfirst surface when the prying device is manipulated to overcome theaforesaid mechanical force; said last recited means comprising a liftpin having an enlarged head with the head extending above said firstsurface when said prying device is manipulated to overcome themechanical force.

3. A circuit interrupter comprising a base, a circuit breaker mounted tosaid base, a fuse means operatively connected to said circuit breaker,securing means removably mounting said fuse means to said base; saidfiuse means being comprised of a cover and a fuse mounted to said cover;said fuse having a first and a second terminal; a third and a fourthterminal mounted to said base and removably engaged with said first andsaid second terminals, respectively; means carried by said cover andoperatively positioned. with respect to said securing means so as to beengageable by and cooperable with a prying device which utilizes saidsecuring means as a fulcrum to thereby readily overcome the mechanicalforce which accompanies the engagement between said fuse terminals andsaid base mounted terminals when said fuse means is mounted to saidbase; said securing means being comprised of a screw passing through aclearance hole of said cover; one end of said screw having an enlargedhead and the other end of said screw having threads mated with athreaded aperture in said base; said head being positioned beyond afirst surface of said cover when said screw is at the entrance of saidaperture; said means carried by said cover extending above said coverfirst surface when the prying device is manipulated to overcome theaforesaid mechanical force; said last recited means comprising a liftpin having an enlarged head with the head extending above said firstsurface when said prying device is manipulated to overcome themechanical force; said cover having a recess in said first surfaceconstructed and operatively positioned to receive said head of said liftpin.

4. A circuit interrupter comprising a base, a circuit breaker mounted tosaid base, a fuse means operatively connected to said circuit breaker,securing means removably mounting said fuse means to said base; saidfuse means being comprised of a cover and a fuse mounted to said cover;said fuse having a first and a second terminal; a third and a fourthterminal mounted to said base and removably engaged with said first andsaid second terminals, respectively; means carried by said cover andoperatively positioned with respect to said securing means so as to beengageable by and cooperable with a prying device which utilizes saidsecuring means as a fulcrum to thereby readily overcome the mechanicalforce which accompanies the engagement between said fuse terminals andsaid base mounted terminals when said fuse means is mounted to saidbase; said securing means being comprised of a screw passing through aclearance hole of said cover; one end of said screw having an enlargedhead and the other end of said screw having threads mated with athreaded aperture in said base; said head being positioned beyond afirst surface of said cover when said screw is at the entrance of saidaperture; said means carried by said cover extending above said coverfirst surface when the prying device is manipulated to overcome theaforesaid mechanical force; said last recited means comprising a liftpin having an enlarged head with the head extending above said surfacewhen said prying device is manipulated to overcome the mechanical force;said cover having a recess in said first surface constructed andoperatively positioned to receive said head of said lift pin; biasingmeans urging said head of said lift pin into said recess.

5. A circuit interrupter comprising a base, a circuit breaker mounted tosaid base, a fuse means operatively connected to said circuit breaker,securing means removably mounting said fuse means to said base; saidfuse means being comprised of a cover and a fuse mounted to said cover;said fuse having a first and a second terminal; a third and a fourthterminal mounted to said base and removably engaged with said first andsaid second terminals, respectively; means carried by said cover andoperatively positioned with respect to said securing means so as to beengageable by and cooperable with a prying device which utilizes saidsecuring means as a fulcrum to thereby readily overcome the mechanicalforce which accompanies the engagement between said fuse terminals andsaid base mounted terminals when said fuse means is mounted to saidbase; said securing means being comprised of a screw passing through aclearance hole of said cover; one end of said screw having an enlargedhead and the other end of said screw having threads mated with athreaded aperture in said base; said head being positioned beyond afirst surface of said cover when said screw is at the entrance of saidaperture; said means carried by said cover extending above said coverfirst surface when the prying device is manipulated to overcome theaforesaid mechanical force; said last recited means comprising a liftpin having an enlarged head with the head extending above said firstsurface when said prying device is manipulated to overcome themechanical force; said cover having a recess in said first surfaceconstructed and operatively positioned to receive said head of said liftpin; said recess including a notched extension projecting toward saidcover clearance hole whereby the prying device may conveniently beworked to a position below the head of said lift pin.

6. A first assembly comprising a screw and a member having a clearancehole operatively positioned to receive said screw which will removablymount said first assembly to a second assembly; said first assemblyincluding first means operatively positioned with respect to said holeto be engaged by and cooperate with a prying device which utilizes saidscrew as a fulcrum so as to assist in dismounting said first assemblyfrom said second assembly; said first means comprising a lift pin havingan enlarged head; said lift pin having limited axial movement.

7. A first assembly comprising a screw and a member having a clearancehole operatively positioned to receive said screw which will removablymount said first assembly to a second assembly; said first assemblyincluding first means operatively positioned with respect to said holeto be engaged by and cooperate with a prying device which utilizes saidscrew as a fulcrum so as to assist in dismounting said first assemblyfrom said second assembly; said first means comprising a lift pin havingan enlarged head; said pin having limited axial movement and beingmovable to a first position wherein said enlarged head is disposedwithin the confines of a recess of said member in said first surfacethereof.

8. A first assembly comprising a screw and a member having a clearancehole operatively positioned to receive said screw which will removablymount said first assembly to a second assembly; said first assemblyincluding first means operatively positioned with repsect to said holeto be engaged by and cooperate with a prying device which utilizes saidscrew as a fulcrum so as to assist in dismounting said first assemblyfrom said second assembly; said first means comprising a lift pin havingan enlarged head; said pin having limited axial movement and beingmovable to a first position wherein said enlarged head is disposedwithin the confines of a recess of said member in said first surfacethereof; means biasing said lift pin to said first position.

9. A first assembly comprising a screw and a member 'having a clearancehole operatively positioned to receive said screw which will removablymount said first assembly to a second assembly; said first assemblyincluding first means operatively positioned with respect to said holeto be engaged by and cooperate with a prying device which utilizes saidscrew as a fulcrum so as to assist in dismounting said first assemblyfrom said second assembly; said first means comprising a lift pin havingan enlarged head; said pin being movable to a first position whereinsaid enlarged head is disposed within the confines of a recess of saidmember in said first surface thereof; means biasing said lift pin tosaid first position; said assembly including a plurality of fuses andmeans for securing said plurality of fuses to said member.

References Cited in the file of this patent UNITED STATES PATENTS2,647,244 Dewey et a1. July 28, 1953 2,863,969 Edmunds Dec. 9, 1958FOREIGN PATENTS 486,218 Great Britain June 1, 1938

